Microparticle sorting device, and method and program for sorting microparticles

Provided are a microparticle sorting device, and a method and a program for sorting microparticles capable of stabilizing sorting performance over a prolonged period of time. The microparticle sorting device includes an imaging element and a controller. The imaging element obtains an image of fluid and fluid droplets at a position where the fluid discharged from an orifice which generates a fluid stream is converted into the fluid droplets. The controller controls driving voltage of an oscillation element which gives oscillation to the orifice and/or controls a position of the imaging element based on a state of the fluid in the image and/or a state of a satellite fluid droplet. The satellite fluid droplet does not include microparticles and exists between the position, where the fluid is converted into the fluid droplets, and a fluid droplet, among fluid droplets including the microparticles, which is closest to the position where the fluid is converted into the fluid droplets.